Refrigeration system including charge checking means



Oct. 27, 1964 H. M. BRODY 3,153,913

REFRIGERATION SYSTEM INCLUDING CHARGE CHECKING MEANS Filed Sept. 10, 1963 2 HERBERT M. exact)? 34 27 BY &

H s ATTORN Ev United States Patent 3,153,913 REFRIGERATION SYSTEM rncrunmo cannon crmcnnso MEANS Herbert M. Brody, Tyler, Tex., assignor to General Electric Company, a corporation of New York Filed Sept. 10, 1963, Ser. No. 307,835 9 Claims. (ill. 62-125) The present invention relates to refrigeration systems including means for checking the charge of refrigerant contained therein and is particularly concerned with a heat pump comprising a reversible refrigerant circuit including a container adapted to both store a portion of the refrigerant charge during operation of the heat pump on the heating cycle and to provide means for checking the total refrigerant charge in the circuit.

It is well known that the optimum operation of a refrigeration system comprising a compressor, a pair of heat exchangers and fixed flow control means for controlling the fiow of refrigerant between the heat exchangers is affected by the amount of refrigerant in the system. It is highly desirable therefore that such a system be provided with simple and effective means for determining the actual refrigerant charge contained in the system particularly in the field servicing thereof. While several methods are presently available to the serviceman, none have been completely acceptable. One method comprises evacuating the system and recharging the system with a new and accurately weighed charge of refrigerant. This is wasteful in that most or all of the refrigerant in the system is lost during the evacuation. Another known method, which comprises the comparison of the system performance with predetermined performance curves and the addition or removal of refrigerant as required, is time consuming and frequently requires the provision of a plurality of performance curves for different ambient or operating conditions.

The present invention has as its principal object the provision of a refrigeration system including a refrigerant storage container between the heat exchangers and means whereby, independent of ambient conditions, substantially all of the refrigerant in the system can be transferred to this container for charge checking purposes.

A more specific object of the invention is to provide a heat pump including a reversible refrigeration system, means including a container for automatically changing the effective circulating refrigerant charge upon reversal of flow of refrigerant through the circuit and means whereby this container can be employed for accurately measuring the total refrigerant charge in the circuit.

Further objects and advantages of the invention will become apparent as the following description proceeds and the features of novelty which characterize the in vention will be pointed out with particularity in the claims annexed to and forming a part of this specification.

In accordance with a preferred embodiment of the present invention, there is provided a refrigeration system of the reversible type comprising an indoor heat exchanger, flow restricting means and an outdoor heat exchanger series-connected in a closed refrigerant circuit and a compressor and reversing valve means for reversibly connecting the compressor to the heat exchangers for effecting flow of refrigerant through the circuit in either direction. A refrigerant container is provided between the two heat exchangers and is connected thereto in such a manner that a portion of the refrigerant charge will be stored in the container during operation of the system on the heating cycle. This container also has a total capacity such that it is capable of Containing substantially the entire optimum liquid refrigerant charge for the system. For the purpose of determining the total amount of refrigerant in the system, the upper por- "ice tion of the container is connected by means of a fixed flow restrictor and a normally closed valve to a low pressure portion of the circuit between the indoor heat exchanger and the compressor inlet and means comprising a normally open valve is provided between the container and the indoor heat exchanger. With the normally open valve closed and the normally closed valve opened, operation of the compressor causes substantially all of the refrigerant charge to be collected as a liquid in the container, which is also provided with means for indicating the total amount of liquid so collected.

For a better understanding of the invention reference may be had to the accompanying drawing in which:

FIGURE 1 is a diagrammatic illustration of a refrigeration system embodying the present invention; and

FIGURE 2 is a diagrammatic illustration of a portion of a refrigeration system illustrating a modification of the present invention.

Referring to FIGURE 1 of the drawing, there is shown one embodiment of the present invention in the form of a heat pump comprising a split refrigeration system comprising an indoor unit 1 and an outdoor unit 2 which are adapted to be connected in the field during installation of the heat pump by means of refrigerant lines 3 and 4, the lengths of which will obviously depend upon the distance between the two units in any particular installation. The line 4 comprises part of a longer conduit generally indicated by the reference numeral 5 for connecting an indoor heat exchanger 6 forming part of the indoor unit 1 with an outdoor heat exchanger 7 forming a part of the outdoor unit 2.

The conduit 5 also includes flow control or flow restricting means for maintaining the pressure difference between the indoor heat exchanger 6 and the outdoor heat exchanger 7. in the embodiment of the invention shown in' FIGURE 1, the indoor unit 1 includes flow control means in the form of a capillary 8 and a bypass line including a check valve 9 which bypasses refrigerant around the capillary 8 when the heat pump is operated as a heating unit and the indoor heat exchanger is functioning as a condenser. The outdoor unit 2 comprises flow control means in the form of a capillary 10 and a bypass line including a check valve 11 which bypasses refrigerant around the capillary 10 when the heat pump unit is operating on the cooling cycle in which the outdoor heat exchanger 7 functions as a condenser. While separate capillaries S and 1d are provided for controlling the refrigerant flow on the heating and cooling cycles, it will be understood that a single capillary or equivalent flow control means may be employed.

A compressor 15 having an inlet 16 connected to a suction line 17 and an outlet 18 connected to a discharge line 19 and a reversing valve 2% connected to the suction and discharge lines provide means for effecting flow of refrigerant through the refrigerant circuit including the two heat exchangers in either direction whereby the indoor unit 1 may be operated either as a heating unit in which the indoor heat exchanger 6 functions as a condenser or as a cooling unit in which the indoor heat exchanger 6 functions as an evaporator. The compressor and reversing valve may be supphed as a separate unit or may be part of either of the units 1 and 2. In the illustrated embodiment of the invention, they form part of the outdoor unit 2 in which case the reversing vmve is connected to the outdoor heat exchanger 7 by means of a conduit 21 and to the indoor heat exchanger by means of a conduit 22, the line 3 and the conduit 24.

For the optimum operation of a heat pump of this type comprising fixed fiow control means for controlling the pressure difierential between the two heat exchangers, a smaller circulating charge is desired on the heating cycle than on the cooling cycle. To provide a decrease in the effective refrigerant charge when the heat pump is changed over from operation on the cooling cycle to the heating cycle, there is provided a container 26 between the indoor heat exchanger 6 and the-flow restricting means. This container 26 is connected into the conduit 5. More specifically, it is connected to the indoor heat exchanger 6 by means of a conduit or line 27 having one end 28 thereof opening into the bottom of the container 26 and to the restricting means by a second line 29 having one end 30 thereof communicating with the container 26 at an intermediate point above the end 28 of the conduit 2'7 such that the volume of the container 26 between these two points of communication is substantially equal to the difierence between the optimum refrigerant charges for the system on the cooling and heating cycles.

Thus it will be seen that the indoor heat exchanger 6, the container 26, the flow restricting means in the form of the capillaries 8 and 10, and the outdoor heat exchanger 7 are connected to form a closed refrigerant circuit including the compressor 15 and the reversing valve 29 so that depending upon the position of the reversing valve 26', the compressor 15 will efiect flow of refrigerant through the circuit in either direction.

More specifically, on the cooling cycle operation of the heat pump, the compressor discharges compressed refrigerant through the discharge line 19 and the reversing valve 20 into the outdoor heat exchanger 7. The condensed refrigerant from the outdoor heat exchanger 7 bypasses the capillary through the check Valve 11 but flows through the capillary 8 into the container 26. The capillary 8 is designed to maintain the desired pressure differential between the outdoor and indoor heat exchangers .on the cooling cycle. The refrigerant passes through the container 26 and the line 27 into the indoor heat exchanger 6 where it is evaporated by absorbing heat from the surrounding atmosphere whereby the air in the dwelling or other structure being conditioned by the heat pump is cooled. The gaseous refrigerant is withdrawn from the heat exchanger 6 through the low pressure lines 24, 3 and 22 and the suction line 7 into the inlet 16 for the compressor 15. Since some evaporation of liquid refrigerant may take place on the cooling cycle in the container 26, this container is preferably positioned relatively close to the indoor heat exchanger 6 and the air from the enclosure is passed over both the indoor heat exchanger 6 and the container 26.

When the reversing valve 2%) is reversed for operation of the system on the heating cycle, hot compressed refrigerant from the compressor is discharged through the discharge line 19 and the lines 22, 3 and 24 into the indoor heat exchanger 6 where the hot compressed refrigerant is condensed giving up its heat of condensation to the space being conditioned. The condensed or liquid refrigerant flows through the conduit 27 into the container 26. Liquid refrigerant will collect in the container 26 until the level thereof reaches the end 36 of the line 29 connecting the container to the flow restricting means.

obtain the optimum operating characteristics. To this end, the container 26 is made of a capacity sufficient to contain substantially the total optimum charge of refrigerant in liquid form and means are provided as part of the heat pump for transferring substantially the entire charge to the container 26 for charge measuring purposes. Specifically, in the embodiment of the invention shown in FIGURE 1, there is provided a charge checking conduit 33 connecting the upper end of the container 26 with the line 24 forming part of the indoor unit. This conduit 33 includes a normally closed valve 32 and a flow restrictor 31 in the form of a capillary having a sufficient flow restriction so that under certain conditions of operation of the system, all or substantially all of the total charge of refrigerant will collect as a liquid in the container 26.

More specifically, for charge checking purposes, the heat pump is operated on the cooling cycle and a normally open valve 34 provided in the line 27 connecting the indoor heat exchanger 6 with container 26 is closed while the normally closed valve 32 in the charge checking conduit 33 is opened. Closing of the valve 34 prevents flow of liquid refrigerant to the indoor heat exchanger 6. In other words the liquid refrigerant flowing into the con. tainer 26 can then no longer flow into the indoor coil 6 while any liquid refrigerant contained in the indoor heat exchanger 6 will be evaporated and returned to the compressor through the low pressure conduits 24, 3 and 22. The refrigerant condensed in the indoor heat exchanger 7 during the charge checking cycle of operation flows through the capillary 8 into the container 26 where it is maintained in a liquid or condensed state by the pressure maintained in the container 26 by means of the flow restrict-or 31. During the charge checking cycle, any liquid refrigerant stored in any lower pressure part of the system is transferred to the container 26. For the purpose of measuring the charge of refrigerant so collected in the container 26 there is provided a liquid-gas interface level indicating means, such as a bleed cock or a sight glass 37 positioned in the upper portion of the con tainer 26 at a point or level such that the liquid-gas interface at the level of the indicating means indicates that the system contains the optimum charge of refrigerant.

So long as the compressor 15 is operatingduring the charge checking cycle, a relatively small amount of the liquid refrigerant contained in the container 26 will be evaporated and withdrawn by the compressor through the flow restrictor 31 so that under some circumstances it may be diflicult to observe with positive accuracy a liquid-gas interface at the indicating means 37. Accord ingly, in a preferred form of the invention, there is pro vided a normally open valve 38 in the conduit 5 so that i valve 38 can be closed to prevent reverse flow of The volume of liquid so collected represents the difference in the optimum charges on the heating and cooling cycles. After this volume has collected in container 26,

liquid refrigerant flows through the check valve 9 to the container 26 provides means for obtaining a difference in the efiective or circulating charge of refrigerant on the two cycles of operation of the heat pump. In accordance with the present invention the container 26 also provides means for checking or measuring the total charge of refrigerant in the system so that refrigerant may be either added to or removed from the system to refrigerant from the container 26 and the compressor stopped so that a static reading of the liquid level within the container 26 can be obtained. Since the desired total or optimum charge of refrigerant for any split system of the type shown in FIGURE 1 must take into consideration the liquid storage capacity of the line 4, the valve'38 is desirably positioned in the outdoor unit 2 closely adjacent the connection of that unit to the line 4. Thus when the valve 38 is closed and the compressor 15 stopped, that portion of the system between the valve 38 and the container 26 which includes the connecting conduit or line 4, the capillary 8 and the bypass line including the check valve 9 becomes filled with liquid refrigerant and in effect becomes part of the container 26 insofar as the charge measurement is concerned. Under these static conditions the amount of refrigerant collected in the container 26 and the adjacent portions of the system can be accurately determined and refrigerant either added -to the system or withdrawn from the system through the servicing valve 39 provided between the valve 34 and the valve 38 until a liquid-gas interface noted at the indicator 37.

When the system has been properly charged, valve 32 is closed and valves 34 and 38 opened to restore the system for normal operation on either the heating or cooling cycle depending upon the position of the reversing valve 20.

From the foregoing it will be seen that there has been provided a simple and effective means for accurately determining the refrigerant charge in a refrigeration system which is operable under any ambient or operating conditions and which does not require the use of charts or equivalent means by the field serviceman.

The sizing or flow rate of the flow restrictor 31 is not particularly critical provided that the refrigerant flow through the system during the charge measuring cycle is substantially less than that obtained under ordinary conditions of normal operation. The restriction or flow rate during the charge measuring cycle should be such that the compressor will operate at a relatively low suction pressure and will pump the low pressure portions of the system, including the indoor heat exchanger 6, dry of all liquid so that the low pressure portions of the system will contain only relatively low density refrigerant vapor. In general, flow rates up to about 50% of the normal flow rate which occurs in the system due to the restriction of the capillary 8 under standard rating conditions for cooling may be employed with the understanding that the level or position of the charge measuring means such as the sight g ass will be determined to some extent by the charge checking flow rate built into the system in the form of the restrictor 31. The normal flow rate under standard rating conditions for cooling as prescribed by .the Air Conditioning and Refrigeration Institute is the flow rate under conditions including an air flow not to exceed 37.5 cubic feet per minute per 1000 Btu/h. to the indoor heat exchanger with the air entering the indoor heat exchanger or coil having an 80 F. dry bulb temperature and a 67 F. wet bulb temperature. The outdoor conditions are 95 F. dry bulb temperature and 75 F. wet bulb temperature.

The optimum sizing or flow rate of the restriction or restrictor 31 for any given system may also depend upon a number of other factors such as the amount of refrigerant flow necessary for cooling the compressor motor during operation of the system on the charge measuring cycle and the pressure diiferentials which the compressor can tolerate without damage to its components. Therefore, the term substantial flow restriction as used with reference to the restriotor 31 is intended to refer to a flow restriction such that during operation of the system on the charge determining or measuring cycle substantially all of the charge will collect as a liquid and high pressure gas on the high pressure side of the system ahead of the flow restrictor 31 and all of the remaining portions of the system will contain only gaseous refrigerant at lower than normal densities. Since the low pressure gaseous refrigerant remaining in some portions of the system as well as any high density refrigerant contained within the container 26 and in the portion of the conduit 33 ahead of the restrictor 31 represent only a small part of the total charge, the amount of liquid refi'igerant contained within the container 26 and associated high pressure volumes under charge measuring conditions in an accurate measurement of the total charge.

FIGURE 2 illustrates a modification of the present invention in which the charge checking operation is carried out by operating the heat pump on the cooling or heating cycle. The system of FIGURE 2 also differs from that shown in FIGURE 1 in that it is an integral or unitary rather than a split system. in FIGURE 2, the same reference numerals have been employed to indicate the same or similar parts or elements.

During operation of the heat pump shown in FIGURE 2 on the cooling cycle, hot compressed refrigerant discharged from the compressor flows through the reversing valve 20 and the conduit or line 21 into the outdoor heat exchanger 7 where it is condensed. The condensed or liquid refrigerant flows through the check valve 11, the capillary 8 and the container 26 into the indoor heat exchanger 6 where it is evaporated to cool the air from the enclosure. The vaporized refrigerant is withdrawn from the indoor heat exchanger 6 through a line 41 connecting the indoor heat exchanger to the valve 26 and this gaseous refrigerant after passing through the valve 20 enters the compressor through the suction line 17 During operation on the heating cycle, hot compressed refrigerant is discharged by the compressor through the valve 20 to the indoor heat exchanger 6 where it is condensed to Warm the air from the enclosure. The condensed refrigerant passes into the container 26 through the line 2'7. Some of this liquid refrigerant is stored, as previously described, in the container 26 until the level of the liquid refrigerant reaches the end 3% of the conduit 29. Liquid refrigerant is then discharged through the conduit 2?, the check valve 9 and the capillary 10 into the outdoor heat exchanger 7 where it evaporates picking up heat from the outdoor atmosphere. The evaporated refrigerant flows through the line 21, the valve 2% and into the compressor through the suction line 17.

The principal difference between the system shown in FIGURE 2 and that shown in FIGURE 1 is the positioning of the valve corresponding to the valve 38 in the system of FIGURE 1. Instead of forming part of the outdoor portion of the system as shown in FIGURE 1, this valve indicated by the numeral 38a, is positioned in the conduit 29 between the container 26 and the flow restricting means or more specifically the capillary 8.

With the valves 34 and 38a arranged on opposite sides of the container 26, the charge in the system may be checked by operating the system on either the heating or the cooling cycle. When the charge is checked during operation on the cooling cycle valve 34 is closed, valve 32 is opened and the charge in the system collects as a liquid, primarily in the container 26, in the same manner as during the charge checking of the system of FIGURE 1.

In order that the charge may also be checked on the heating cycle the conduit 33 including the flow restriction 31 is connected directly to the suction line 17 leading from the reversing valve 20 to the compressor 15. Operation of the system on the heating cycle with the valve 38a closed and the valve 32 open causes substantially all of the refrigerant in the system to be collected as a liquid in the container 26 ahead of the restrictor '51.

On either cycle of operation the static measurement of the charge is obtained by closing both of the valves 34- and 38a after the refrigerant has been transferred to the container 2 6.

While there has been shown and described specific embodiments of the present invention, it is to be understood that the invention is not limited thereto and it is intended by the appended claims to cover all modifications within the spirit and scope of the invention.

What I claim as new and desire to secure by Letters Patent of the United States is:

l. A refrigeration system comprising:

a first heat exchanger,

a conduit including flow restricting means, and

a second heat exchanger series-connected in a closed refrigerant circuit,

means including a compressor having a suction line for withdrawing low pressure refrigerant from said first heat exchanger and discharging high pressure refrigerant to said second heat exchanger,

a container having a liquid refrigerant storage capacity substantially equal to at least the liquid volume of the total refrigerant charge for said system, said container being connected in said conduit between said heat exchangers,

normally open valve means in said conduit between said container and said first heat exchanger and adapted when closed to stop the flow of refrigerant fromsaid container to said first heat exchanger,

7 a charge checking line including a normally closed valve means and a fiow restrictor having a substantial fiow restriction connecting said container adjacent the top thereof with said suction line,

whereby when said system is operated with said normally closed valve means open and said normally open valve means closed, substantially all of the refrigerant charge in said system will collect as a liquid in said container,

and means for indicating the total quantity of liquid refrigerant so collected.

2. A heat pump comprising:

an indoor heat exchanger,

a first conduit,

a container,

a second conduit including flow restricting means,

and an outdoor heat exchanger series-connected in a closed refrigerant circuit,

means including a compressor having an inlet and an outlet and reversing valve means for reversibly connecting said compressor to said heat exchangers for effecting flow of refrigerant through said circuit in either direction whereby said heat pump may be operated on a cooling cycle with said indoor heat exchanger functioning as an evaporator or on a heating cycle with said outdoor heat exchanger functioning as an evaporator,

a third conduit including a flow restrictor having a substantial flow restriction and a normally closed valve connecting the upper portion of said container to a portion of said circuit directly connected to said compressor inlet,

and means for stopping flow of refrigerant from said container to one of said heat exchangers whereby when said heat pump is operated on the cycle in which said one of said heat exchangers is functioning as an evaporator and said valve in said third conduit is open, substantially all of the refrigerant in said circuit will collect as a liquid in said container,

said container including means for indicating when the refrigerant so collected in said container is equal to the proper total charge for said system;

3. A heat pump comprising:

an indoor heat exchanger,

a first conduit,

a container,

a second conduit including flow restricting means,

and an outdoor heat exchanger series-connected in a closed refrigerant circuit,

means including a compressor having an inlet and an outlet and reversing valve means for reversibly connecting said compressor to said heat exchangers for eifecting flow of refrigerant through said circuit in either direction whereby said heat pump may be operated on a cooling cycle with said indoor heat exchanger functioning as an evaporator or on a heating cycle with said outdoor heat exchanger functioning as an evaporator,

said first conduit having an end thereof communicating with said container adjacent the bottom thereof,

said second conduit having an end thereof communicating with said container at a point above said first conduit end a distance such that the volume of the container between said first and second conduit ends is substantially equal to the volume of the difference between the optimum charges for said system on the cooling and heating cycles so that said difference will be stored in said container when said pump is being operated on the heating cycle,

a third conduit including a flow restrictor having a substantial flow restriction and a normally closed valve connecting the upper portion of said container 8 to a portion of said circuit directly. connectedto said compressor inlet,

and means for stopping flow of refrigerant from said container to one of said heat exchangers whereby when said heat pump is operated on the cyclein which said one of said heat exchangers is functioning as an evaporator and said valve in said third conduit is open, substantially all of the refrigerant in said circuit will collect as a liquid in said' con.-

tainer,

said container including means for indicating when the refrigerant so collected in said container is equal to the proper total charge for said system.

4. A heat pump comprising:

an indoor heat exchanger,

a first conduit including a normally open valve,

a container,

a second conduit including flow restricting means and a normally open valve,

and an outdoor heat exchanger series-connected in a closed refrigerant circuit,

means including a compressor having an inlet and an outlet and reversing valve means for reversibly connecting said compressor to said heat exchangersfor effecting flow of refrigerant through said circuit in either direction whereby said heat pump may be operated on a cooling cycle with said indoor heat exchanger functioning as an evaporator or on a heating cycle with said indoor heat exchanger functioning as a condenser, 7

said first conduit having an end opening into said container adjacent the bottom thereof,

said second conduit having an end opening into said container above said first conduit connection a distance such that the volume of the container between said first and second conduit ends is substantially equal to the difference in volume of the optimum refrigerant charges for said system on the cooling and heating cycles and whereby said ditference will be stored as a liquid in said container when said pump is being operated on the heating cycle,

a third conduit including a flow restrictor having a substantial flow restriction and a normally closed valve connecting the upper portion of said container to a portion of said circuit between said indoor heat exchanger andsaid compressor inlet,

and means for, stopping flow of refrigerant through said first conduit whereby, when said heat pump is operated on the cooling cycle and said valve in said third conduit is open, substantially all of the refrigerant in said circuit will collect as a liquid in said container,

said container including means for indicating when the refrigerant so collected in said container is equal to the proper total charge of said system. if

5. A heat pump comprising:

an indoor heat exchanger, 7

a first conduit including a normally open valve,

a container adapted to store substantially the entire refrigerant charge for said heat pump, a V a a second conduit including flow restricting means and a normally open valve, 7 7

and an outdoor heat exchanger seriesconnected in a closed refrigerant circuit, 7

means including a compressor having an inlet and an outlet and reversing valvemeans for reversibly connecting said compressor to said heat exchangers for effecting flow of refrigerant through said circuit in either direction whereby said heat pump may be operated on a cooling cycle with said indoor coil functioning as an evaporator or on a heating cycle with said indoor coil functioning as a condenser,

said first conduit having an end opening into said container adjacent the bottom thereof,

said second conduit having an end opening into an intermediate portion of said container above said first conduit connection a distance such that the volume of the container between said first and second conduit ends is substantially equal to the volumetric difference between the optimum liquid refrigerant charges for said system on the cooling and heating cycles and whereby said difference will be stored as a liquid in said container when said pump is being operated on the heating cycle,

a third conduit including a flow restrictor having a substantial flow restriction and a normally closed valve connecting the upper portion of said container to a portion of said circuit between said indoor heat exchanger and said compressor inlet,

whereby when said heat pump is operated on the cooling cycle with said valve in said first conduit closed and said valve in said third conduit open, substantially all of the refrigerant in said circuit will collect as a liquid in said container,

means for indicating when the refrigerant so collected is equal to the proper total charge for said system,

closing of said valve in said second conduit providing means for preventing reverse flow of the collected refrigerant from said container to permit a static determination of the level of the liquid refrigerant in said container.

6. A refrigeration system comprising:

a condenser,

flow restricting means,

a container having a liquid refrigerant storage capacity at least substantially equal to the liquid volume of the total charge for said system,

and an evaporator series-connected in a closed refrigerant circuit,

means including a compressor having a suction line for withdrawing low pressure refrigerant from said evaporator and discharging high pressure refrigerant to said condenser,

a charge checking line including a flow restrictor having a substantial restriction connecting said container adjacent the top thereof with said suction line,

said charge checking line including normally closed valve means,

normally open valve means between said container and said evaporator and adapted when closed to stop the fiow of refrigerant from said container to said evaporator,

whereby when said system is operated with said normally closed valve means open and said normally open valve means closed, substantially all of the refrigerant charge in said system will collect as a liquid in said container,

means for indicating the total quantity of liquid refrigerant so collected,

and a second normally open valve between said condenser and container and adapted when closed to prevent reverse flow of refrigerant so that when said second valve is closed after the charge is collected in said container a static measurement of said charge can be made.

7. A heat pump comprising:

an indoor heat exchanger,

a first conduit,

a container capable of holding substantially the entire refrigerant charge for said heat pump,

a second conduit,

flow restricting means,

and an outdoor heat exchanger series-connected in a closed refrigerant circuit,

means including a compressor having an inlet and an outlet port and reversing valve means for reversibly connecting said compressor to said heat exchangers for effecting fiow of refrigerant through said circuit in either direction whereby said heat pump may be operated on a cooling cycle with said indoor coil functioning as an evaporator or on a heating cycle with said indoor coil functioning as a condenser,

said first conduit having an end thereof communicating with said container adjacent the bottom thereof,

said second conduit having an end thereof communicating with said container at a point above said first conduit end a distance such that the volume of the container between said first and second conduit ends is substantially equal to the difference in volume of the optimum charges for said system on the cooling and heating cycles so that said difference will be stored in said container when said pump is being operated on the heating cycle,

a third conduit including a flow restrictor having a substantial flow restriction and a normally closed valve connecting the upper portion of said container to a portion of said circuit between said indoor heat exchanger and said compressor inlet,

and means for stopping flow of refrigerant through said second conduit whereby when said heat pump is operated on the heating cycle and said valve in said third conduit is open, substantially all of the refrigerant in said circuit will collect as a liquid in said container,

said container including means for indicating the liquid level of refrigerant so collected in said container.

8. A heat pump comprising:

an indoor heat exchanger,

a first conduit including a normally open valve,

a container capable of storing substantially the entire optimum charge of liquid refrigerant for said pump,

a second conduit including flow restricting means and a normally open valve,

and an outdoor heat exchanger series-connected in a closed refrigerant circuit,

means including a compressor having an inlet and an outlet port and reversing valve means for reversibly connecting said compressor to said heat exchangers for effecting flow of refrigerant through said circuit in either direction whereby said heat pump may be operated on a cooling cycle with said indoor coil functioning as an evaporator or on a heating cycle with said indoor coil functioning as a condenser,

said first conduit having an end thereof communicating with said container adjacent the bottom thereof,

said second conduit having an end thereof communicating with said container at a point above said first conduit end a distance such that the volume of the container between said first and second conduit ends is substantially equal to the difierence in volume of the optimum charges for said system on the cooling and heating cycles so that said differences will be stored in said container when said pump is being operated on the heating cycle,

a third conduit including a flow restrictor having a flow rate not exceeding one-half the flow rate of said flow restricting means and a normally closed valve connecting the upper portion of said container to a portion of said circuit between said indoor heat exchanger and said compressor inlet,

whereby closing of said valve in said second conduit to stop flow of refrigerant through said second conduit when said heat pump is operated on the heating cycle and said valve in said third conduit is open, causes substantially all of the refrigerant in said circuit to collect as a liquid in said container,

said container including means for indicating whether the refrigerant so collected in said container is substantially equal to the proper total charge for said system,

closing of said valve in said first conduit providing means for preventing reverse flow of the collected refrigerant from said container to permit a static 11 determination of the liquid refrigerant collected in said container.

9. A refrigeration system comprising:

a condenser,

a container having a liquid refrigerant storage capacity at least equal to the liquid volume of the total refrigerant charge for said system,

a flow restricting means,

and an evaporator series-connected in a closed refrigerant circuit,

means including a compressor having a suction line for Withdrawing low pressure refrigerant from said evaporator and discharging refrigerant to said condenser,

the connection of said container to said flow restricting means communicating with said container at a point intermediate the top and bottom thereof,

a charge checking line including a normally closed valve means and a flow restrictor having a substan tial flow restriction connecting said container adjacent the top thereof with said suction line,

means between said container and said flow restricting means for stopping flow of refrigerant from said container whereby when said system is operated with said normally closed valve means open, substantially all of the refrigerant charge in said system will collect as a liquid in said container,

and means for indicating the total quantity of liquid refrigerant collected in said container.

References Cited in the file of this patent,

UNITED STATES PATENTS Schliemann Aug. 4, 1914 2,157,145 Ridge May 9, 1939 2,715,317 Rhodes Aug. 16,1955 3,009,335 Alsing' Nov. 21, 1961 3,110,164 Smith Nov. 12, 1963 

1. A REFRIGERATION SYSTEM COMPRISING: A FIRST HEAT EXCHANGER, A CONDUIT INCLUDING FLOW RESTRICTING MEANS, AND A SECOND HEAT EXCHANGER SERIES-CONNECTED IN A CLOSED REFIGERANT CIRCUIT, MEANS INCLUDING A COMPRESSOR HAVING A SUCTION LINE FOR WITHDRAWING LOW PRESSURE REFRIGERANT FROM SAID FIRST HEAT EXCHANGER AND DISCHARGING HIGH PRESSURE REFRIGERANT TO SAID SECOND HEAT EXCHANGER, A CONTAINER HAVING A LIQUID REFRIGERANT STORAGE CAPACITY SUBSTANTIALLY EQUAL TO AT LEAST THE LIQUID VOLUME OF THE TOTAL REFRIGERANT CHARGE FOR SAID SYSTEM, SAID CONTAINER BEING CONNECTED IN SAID CONDUIT BETWEEN SAID HEAT EXCHANGERS, NORMALLY OPEN VALVE MEANS IN SAID CONDUIT BETWEEN SAID CONTAINER AND SAID FIRST HEAT EXCHANGER AND ADAPTED WHEN CLOSED TO STOP THE FLOW OF REFRIGERANT FROM SAID CONTAINER TO SAID FIRST HEAT EXCHANGER, A CHARGE CHECKING LINE INCLUDING A NORMALLY CLOSED VALVE MEANS AND A FLOW RESTRICTOR HAVING A SUBSTANTIAL FLOW RESTRICTION CONNECTING SAID CONTAINER ADJACENT THE TOP THEREOF WITH SAID SUCTION LINE, WHEREBY WHEN SIAD SYSTEM IS OPERATED WITH SAID NORMALLY CLOSED VALVE MEANS OPEN AND SAID NORMALLY OPEN VALVE MEANS CLOSED, SUBSTANTIALLY ALL OF THE REFIGERANT CHARGE IN SAID SYSTEM WILL COLLECT AS A LIQUID IN SAID CONTAINER, AND MEANS FOR INDICATING THE TOTAL QUANTITY OF LIQUID REFRIGERANT SO COLLECTED. 